Electromechanical actuator arrangements have been used for many years to achieve energy-efficient and precise motion of different objects. Typical applications are motion of lenses in optical systems, positioning of objects under a microscope, control of ink jet nozzles, etc.
In a typical prior art rotating electromechanical actuator system, an object to be rotated is attached to a rotating table. The rotating table is moved by action of an electromechanical actuator. The load of the object and the rotating table is acting against a support part, typically by means of rotational bearings. The bearings are typically radial or combined radial and axial bearings. For high precision positioning applications, very high demands are put on the actuator as well as on the bearing arrangements. Typically, the actuator is responsible for the accuracy in the driving direction, i.e. the rotated angle, while the bearing arrangement takes care of the eccentricity as well as the wobble around the rotation axis. The standard rotational bearings of today may provide an eccentricity in the order of below 3 μm. However, wobble is much more difficult to control. In many applications, there are requests of having a wobble that is less than 100 μrad. In order to provide such accuracies, multiple rotational bearings typically have to be provided at different axial positions. This in turn requires precision mounting of the bearings relative each other and also adds on the axial dimension of the rotating actuator system. Typical allowable loads can then be as high as 500 N.
A problem with rotating electromechanical actuator systems of today is that the rotation bearing arrangements require careful alignment and add to the total volume. In order to further reduce sizes of the electromechanical actuator systems while maintaining or even improving the accuracies very expensive solutions according to prior art have to be considered. At the same time, the loads are often much lower than the maximum limit, giving a very high load margin.